Horizontal geometry of trade wind cumuli – aircraft observations from a shortwave infrared imager versus a radar profiler
This study elaborates on how aircraft-based horizontal geometries of trade wind cumulus clouds differ whether a one-dimensional (1D) profiler or a two-dimensional (2D) imager is used. While nadir profiling devices are limited to a 1D realization of the cloud transect size, with limited representativ...
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ftdoajarticles:oai:doaj.org/article:dd953621e5a04c9c9e2416329bc673a4 2023-05-15T18:50:51+02:00 Horizontal geometry of trade wind cumuli – aircraft observations from a shortwave infrared imager versus a radar profiler H. Dorff H. Konow F. Ament 2022-06-01T00:00:00Z https://doi.org/10.5194/amt-15-3641-2022 https://doaj.org/article/dd953621e5a04c9c9e2416329bc673a4 EN eng Copernicus Publications https://amt.copernicus.org/articles/15/3641/2022/amt-15-3641-2022.pdf https://doaj.org/toc/1867-1381 https://doaj.org/toc/1867-8548 doi:10.5194/amt-15-3641-2022 1867-1381 1867-8548 https://doaj.org/article/dd953621e5a04c9c9e2416329bc673a4 Atmospheric Measurement Techniques, Vol 15, Pp 3641-3661 (2022) Environmental engineering TA170-171 Earthwork. Foundations TA715-787 article 2022 ftdoajarticles https://doi.org/10.5194/amt-15-3641-2022 2022-12-30T21:38:45Z This study elaborates on how aircraft-based horizontal geometries of trade wind cumulus clouds differ whether a one-dimensional (1D) profiler or a two-dimensional (2D) imager is used. While nadir profiling devices are limited to a 1D realization of the cloud transect size, with limited representativeness of horizontal cloud extension, 2D imagers enhance our perspectives by mapping the horizontal cloud field. Both require high resolutions to detect the lower end of the cloud size spectrum. In this regard, the payload aboard the HALO (High Altitude and LOng Range Research Aircraft) achieves a comparison and also a synergy of both measurement systems. Using the NARVAL II (Next-Generation Aircraft Remote-Sensing for Validation Studies) campaign, we combine HALO observations from a 35.2 GHz cloud and precipitation radar (1D) and from the hyperspectral 2D imager specMACS (Munich Aerosol Cloud Scanner), with a 30 times higher along-track resolution, and compare their cloud masks. We examine cloud size distributions in terms of sensitivity to sample size, resolution and the considered field of view (2D or 1D). This specifies impacts on horizontal cloud sizes derived from the across-track perspective of the high-resolution imager in comparison to the radar curtain. We assess whether and how the trade wind field amplifies uncertainties in cloud geometry observations along 1D transects through directional cloud elongation. Our findings reveal that each additional dimension, no matter of the device, causes a significant increase in observed clouds. The across-track field yields the highest increase in the cloud sample. The radar encounters difficulties in characterizing the trade wind cumuli size distribution. More than 60 % of clouds are subgrid scale for the radar. The radar has issues in the representation of clouds shorter than 200 m, as they are either unresolved or are incorrectly displayed as single grid points. Very shallow clouds can also remain unresolved due to too low radar sensitivity. Both facts deteriorate ... Article in Journal/Newspaper narval narval Directory of Open Access Journals: DOAJ Articles Atmospheric Measurement Techniques 15 12 3641 3661 |
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Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
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language |
English |
topic |
Environmental engineering TA170-171 Earthwork. Foundations TA715-787 |
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Environmental engineering TA170-171 Earthwork. Foundations TA715-787 H. Dorff H. Konow F. Ament Horizontal geometry of trade wind cumuli – aircraft observations from a shortwave infrared imager versus a radar profiler |
topic_facet |
Environmental engineering TA170-171 Earthwork. Foundations TA715-787 |
description |
This study elaborates on how aircraft-based horizontal geometries of trade wind cumulus clouds differ whether a one-dimensional (1D) profiler or a two-dimensional (2D) imager is used. While nadir profiling devices are limited to a 1D realization of the cloud transect size, with limited representativeness of horizontal cloud extension, 2D imagers enhance our perspectives by mapping the horizontal cloud field. Both require high resolutions to detect the lower end of the cloud size spectrum. In this regard, the payload aboard the HALO (High Altitude and LOng Range Research Aircraft) achieves a comparison and also a synergy of both measurement systems. Using the NARVAL II (Next-Generation Aircraft Remote-Sensing for Validation Studies) campaign, we combine HALO observations from a 35.2 GHz cloud and precipitation radar (1D) and from the hyperspectral 2D imager specMACS (Munich Aerosol Cloud Scanner), with a 30 times higher along-track resolution, and compare their cloud masks. We examine cloud size distributions in terms of sensitivity to sample size, resolution and the considered field of view (2D or 1D). This specifies impacts on horizontal cloud sizes derived from the across-track perspective of the high-resolution imager in comparison to the radar curtain. We assess whether and how the trade wind field amplifies uncertainties in cloud geometry observations along 1D transects through directional cloud elongation. Our findings reveal that each additional dimension, no matter of the device, causes a significant increase in observed clouds. The across-track field yields the highest increase in the cloud sample. The radar encounters difficulties in characterizing the trade wind cumuli size distribution. More than 60 % of clouds are subgrid scale for the radar. The radar has issues in the representation of clouds shorter than 200 m, as they are either unresolved or are incorrectly displayed as single grid points. Very shallow clouds can also remain unresolved due to too low radar sensitivity. Both facts deteriorate ... |
format |
Article in Journal/Newspaper |
author |
H. Dorff H. Konow F. Ament |
author_facet |
H. Dorff H. Konow F. Ament |
author_sort |
H. Dorff |
title |
Horizontal geometry of trade wind cumuli – aircraft observations from a shortwave infrared imager versus a radar profiler |
title_short |
Horizontal geometry of trade wind cumuli – aircraft observations from a shortwave infrared imager versus a radar profiler |
title_full |
Horizontal geometry of trade wind cumuli – aircraft observations from a shortwave infrared imager versus a radar profiler |
title_fullStr |
Horizontal geometry of trade wind cumuli – aircraft observations from a shortwave infrared imager versus a radar profiler |
title_full_unstemmed |
Horizontal geometry of trade wind cumuli – aircraft observations from a shortwave infrared imager versus a radar profiler |
title_sort |
horizontal geometry of trade wind cumuli – aircraft observations from a shortwave infrared imager versus a radar profiler |
publisher |
Copernicus Publications |
publishDate |
2022 |
url |
https://doi.org/10.5194/amt-15-3641-2022 https://doaj.org/article/dd953621e5a04c9c9e2416329bc673a4 |
genre |
narval narval |
genre_facet |
narval narval |
op_source |
Atmospheric Measurement Techniques, Vol 15, Pp 3641-3661 (2022) |
op_relation |
https://amt.copernicus.org/articles/15/3641/2022/amt-15-3641-2022.pdf https://doaj.org/toc/1867-1381 https://doaj.org/toc/1867-8548 doi:10.5194/amt-15-3641-2022 1867-1381 1867-8548 https://doaj.org/article/dd953621e5a04c9c9e2416329bc673a4 |
op_doi |
https://doi.org/10.5194/amt-15-3641-2022 |
container_title |
Atmospheric Measurement Techniques |
container_volume |
15 |
container_issue |
12 |
container_start_page |
3641 |
op_container_end_page |
3661 |
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